// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_BASE_USER_ACTIVITY_USER_ACTIVITY_DETECTOR_H_
#define UI_BASE_USER_ACTIVITY_USER_ACTIVITY_DETECTOR_H_

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/observer_list.h"
#include "base/time/time.h"
#include "ui/base/ui_base_export.h"
#include "ui/events/event.h"
#include "ui/events/platform/platform_event_observer.h"

namespace ui {

class UserActivityObserver;

// Watches for input events and notifies observers that the user is active.
class UI_BASE_EXPORT UserActivityDetector : public ui::PlatformEventObserver {
public:
    // Minimum amount of time between notifications to observers.
    static const int kNotifyIntervalMs;

    // Amount of time that mouse events should be ignored after notification
    // is received that displays' power states are being changed.
    static const int kDisplayPowerChangeIgnoreMouseMs;

    UserActivityDetector();
    ~UserActivityDetector() override;

    // Returns the UserActivityDetector instance if one was created.
    static UserActivityDetector* Get();

    base::TimeTicks last_activity_time() const { return last_activity_time_; }

    void set_now_for_test(base::TimeTicks now) { now_for_test_ = now; }

    bool HasObserver(const UserActivityObserver* observer) const;
    void AddObserver(UserActivityObserver* observer);
    void RemoveObserver(UserActivityObserver* observer);

    // Called when displays are about to be turned on or off.
    void OnDisplayPowerChanging();

    // ui::PlatformEventObserver:
    void WillProcessEvent(const PlatformEvent& platform_event) override { }
    void DidProcessEvent(const PlatformEvent& platform_event) override;

private:
    friend class UserActivityDetectorTest;

    // Returns |now_for_test_| if set or base::TimeTicks::Now() otherwise.
    base::TimeTicks GetCurrentTime() const;

    // Processes the event after it has been converted from a PlatformEvent.
    void ProcessReceivedEvent(const ui::Event* event);

    // Updates |last_activity_time_|.  Additionally notifies observers and
    // updates |last_observer_notification_time_| if enough time has passed
    // since the last notification.
    void HandleActivity(const ui::Event* event);

    base::ObserverList<UserActivityObserver> observers_;

    // Last time at which user activity was observed.
    base::TimeTicks last_activity_time_;

    // Last time at which we notified observers that the user was active.
    base::TimeTicks last_observer_notification_time_;

    // If set, used when the current time is needed.  This can be set by tests to
    // simulate the passage of time.
    base::TimeTicks now_for_test_;

    // If set, mouse events will be ignored until this time is reached. This
    // is to avoid reporting mouse events that occur when displays are turned
    // on or off as user activity.
    base::TimeTicks honor_mouse_events_time_;

    DISALLOW_COPY_AND_ASSIGN(UserActivityDetector);
};

} // namespace ui

#endif // UI_BASE_USER_ACTIVITY_USER_ACTIVITY_DETECTOR_H_
